Spacing tubes (spacers) have been used in order to connect a plurality of printed wiring boards while maintaining a predetermined spacing therebetween.
Regarding the connection of printed wiring boards using a spacing tube, a technique described hereinbelow has been proposed. For example, a mounting method has been proposed in which power signal layers and GND signal layers are exposed on the surfaces of printed wiring boards where a plurality of conductive spacers is joined, and the printed wiring boards are fixed to each other using a conductive spacer which corresponds to the power signal layers and the GND signal layers, respectively. In addition, a mounting method has been proposed in which a single conductive spacer is divided into a plurality of conductive spacers, and a plurality of power signal layers and GND signal layers of printed wiring boards are exposed to correspond to the divided conductive spacers so as to supply a plurality of power signals and GND signals.
A configuration described below may be exemplified as a configuration that connects two printed wiring boards mechanically and electrically using a spacing tube including two conductors which are electrically separated from each other.
For example, a through hole is provided in a central portion of a spacing tube so as to insert a screw therethrough. Two electrically separated conductors are exposed on both end faces which are abutted on the printed wiring boards, respectively. The two conductors are electrically separated from each other in a circumferential direction along an outer edge of the through hole. Each of the printed wiring boards is formed with a wiring pattern corresponding to the two conductors of the spacing tube on a surface where the spacing tube is abutted, and also provided with a through hole through which a screw is inserted. That is, each of the printed wiring boards is formed with two wiring patterns which are divided in a circumferential direction along the outer edge of the through hole. When positioning of the two conductors of the spacing tube and the two wiring patterns formed on each of the printed wiring boards is performed, the bolt is inserted through the through hole of the spacing tube and the through hole of each of the printed wiring boards, and a nut is attached to the bolt from the opposite side, so that the two printed wiring boards are connected with each other with the spacing tube sandwiched therebetween.
According to the aforementioned configuration, the two printed wiring boards are mechanically connected with each other while maintaining a predetermined spacing therebetween through the spacing tube and at the same time, two electrically separated conductive paths are formed between the two printed wiring boards.
However, according to the aforementioned configuration, it is difficult to align the two conductors provided in the spacing tube and the two wiring patterns formed on each of the printed wiring boards. That is, in a case in which the conductors of the spacing tube and the wiring patterns of each of the printed wiring boards are divided in the circumferential directions along the outer edges of the through holes, respectively, it is necessary to strictly perform positioning in the circumferential direction (in the direction around the axis of the spacing tube) when attaching the spacing tube to each of the printed wiring boards so as to prevent short circuit. Accordingly, a work burden increases regarding the positioning of the spacing tube and each printed wiring board.
The following is a reference document.    [Document 1] Japanese Laid-Open Patent Publication No. H08-330699